So in other words, you won't be able to use the HPWM command for that high of a frequency. But as Skimask points out, you can achieve that frequency by setting up the PWM registers manually. As mentioned, section 8.3 of the PIC16F87XA datasheet will explain this. If you get stuck, ask.... I've never set these up before, but I'm pretty confident someone here can guide you.